diff --git a/src/screencast.c b/src/screencast.c
index 6b0014a..15f6a80 100644
--- a/src/screencast.c
+++ b/src/screencast.c
@@ -427,16 +427,20 @@ find_best_window_by_app_id_and_title (const char *app_id,
                                       const char *title)
 {
   ShellIntrospect *shell_introspect = shell_introspect_get ();
+  GPtrArray *windows;
   Window *best_match;
   glong best_match_distance;
-  GList *l;

   best_match = NULL;
   best_match_distance = G_MAXLONG;

-  for (l = shell_introspect_get_windows (shell_introspect); l; l = l->next)
+  shell_introspect_ref_listeners (shell_introspect);
+  shell_introspect_wait_for_windows (shell_introspect);
+
+  windows = shell_introspect_get_windows (shell_introspect);
+  for (size_t i = 0; windows && i < windows->len; i++)
     {
-      Window *window = l->data;
+      Window *window = g_ptr_array_index (windows, i);
       glong distance;

       if (g_strcmp0 (window_get_app_id (window), app_id) != 0)
@@ -454,6 +458,8 @@ find_best_window_by_app_id_and_title (const char *app_id,
         }
     }

+  shell_introspect_unref_listeners (shell_introspect);
+
   /* If even the best match's window title is too different, don't
    * restore it.
    */
diff --git a/src/screencastwidget.c b/src/screencastwidget.c
index 9b30f2d..e95fee2 100644
--- a/src/screencastwidget.c
+++ b/src/screencastwidget.c
@@ -164,8 +164,7 @@ update_windows_list (ScreenCastWidget *widget)
   GtkListBox *window_list = GTK_LIST_BOX (widget->window_list);
   GtkWidget *toplevel;
   GtkWidget *child;
-  GList *windows;
-  GList *l;
+  GPtrArray *windows;

   child = gtk_widget_get_first_child (GTK_WIDGET (window_list));
   while (child)
@@ -181,9 +180,9 @@ update_windows_list (ScreenCastWidget *widget)
     return;

   windows = shell_introspect_get_windows (widget->shell_introspect);
-  for (l = windows; l; l = l->next)
+  for (size_t i = 0; windows && i < windows->len; i++)
     {
-      Window *window = l->data;
+      Window *window = g_ptr_array_index (windows, i);
       GtkWidget *window_widget;

       if (should_skip_window (window, GTK_WINDOW (toplevel)))
diff --git a/src/shellintrospect.c b/src/shellintrospect.c
index 1fa8b93..c2b288d 100644
--- a/src/shellintrospect.c
+++ b/src/shellintrospect.c
@@ -22,16 +22,6 @@
 #include "shell-dbus.h"
 #include "shellintrospect.h"

-enum
-{
-  WINDOWS_CHANGED,
-  ANIMATIONS_ENABLED_CHANGED,
-
-  N_SIGNALS
-};
-
-static guint signals[N_SIGNALS];
-
 struct _Window
 {
   uint64_t id;
@@ -50,7 +40,7 @@ struct _ShellIntrospect

   unsigned int version;

-  GList *windows;
+  GPtrArray *windows;

   int num_listeners;

@@ -60,6 +50,16 @@ struct _ShellIntrospect

 G_DEFINE_TYPE (ShellIntrospect, shell_introspect, G_TYPE_OBJECT)

+enum
+{
+  WINDOWS_CHANGED,
+  ANIMATIONS_ENABLED_CHANGED,
+
+  N_SIGNALS
+};
+
+static guint signals[N_SIGNALS];
+
 static ShellIntrospect *_shell_introspect;

 static void
@@ -70,50 +70,36 @@ window_free (Window *window)
   g_free (window);
 }

-const char *
-window_get_title (Window *window)
-{
-  return window->title;
-}
-
-const char *
-window_get_app_id (Window *window)
-{
-  return window->app_id;
-}
-
-const uint64_t
-window_get_id (Window *window)
-{
-  return window->id;
-}
-
 static void
 get_windows_cb (GObject *source_object,
                 GAsyncResult *res,
                 gpointer user_data)
 {
   ShellIntrospect *shell_introspect = user_data;
+  g_autoptr(GPtrArray) windows = NULL;
   g_autoptr(GVariant) windows_variant = NULL;
   g_autoptr(GError) error = NULL;
   GVariantIter iter;
   uint64_t id;
   GVariant *params = NULL;
-  GList *windows = NULL;

-  g_list_free_full (shell_introspect->windows, (GDestroyNotify) window_free);
-  shell_introspect->windows = NULL;
+  g_clear_object (&shell_introspect->cancellable);

   if (!org_gnome_shell_introspect_call_get_windows_finish (shell_introspect->proxy,
                                                            &windows_variant,
                                                            res,
                                                            &error))
     {
-      g_warning ("Failed to get window list: %s", error->message);
+      if (!g_error_matches (error, G_IO_ERROR, G_IO_ERROR_CANCELLED))
+        g_warning ("Failed to get window list: %s", error->message);
       return;
     }

   g_variant_iter_init (&iter, windows_variant);
+
+  windows = g_ptr_array_new_full (g_variant_iter_n_children (&iter),
+                                  (GDestroyNotify) window_free);
+
   while (g_variant_iter_loop (&iter, "{t@a{sv}}", &id, &params))
     {
       char *app_id = NULL;
@@ -131,64 +117,30 @@ get_windows_cb (GObject *source_object,
         .title = title,
         .app_id = app_id
       };
-      windows = g_list_prepend (windows, window);
+      g_ptr_array_add (windows, window);

       g_clear_pointer (&params, g_variant_unref);
     }

-  shell_introspect->windows = windows;
+  shell_introspect->windows = g_steal_pointer (&windows);
   g_signal_emit (shell_introspect, signals[WINDOWS_CHANGED], 0);
 }

 static void
 sync_state (ShellIntrospect *shell_introspect)
 {
+  g_clear_pointer (&shell_introspect->windows, g_ptr_array_unref);
+
+  g_cancellable_cancel (shell_introspect->cancellable);
+  g_clear_object (&shell_introspect->cancellable);
+  shell_introspect->cancellable = g_cancellable_new ();
+
   org_gnome_shell_introspect_call_get_windows (shell_introspect->proxy,
                                                shell_introspect->cancellable,
                                                get_windows_cb,
                                                shell_introspect);
 }

-GList *
-shell_introspect_get_windows (ShellIntrospect *shell_introspect)
-{
-  return shell_introspect->windows;
-}
-
-void
-shell_introspect_ref_listeners (ShellIntrospect *shell_introspect)
-{
-  shell_introspect->num_listeners++;
-
-  if (shell_introspect->proxy)
-    sync_state (shell_introspect);
-}
-
-void
-shell_introspect_unref_listeners (ShellIntrospect *shell_introspect)
-{
-  g_return_if_fail (shell_introspect->num_listeners > 0);
-
-  shell_introspect->num_listeners--;
-  if (shell_introspect->num_listeners == 0)
-    {
-      g_list_free_full (shell_introspect->windows,
-                        (GDestroyNotify) window_free);
-      shell_introspect->windows = NULL;
-    }
-}
-
-gboolean
-shell_introspect_are_animations_enabled (ShellIntrospect *shell_introspect,
-                                         gboolean        *out_animations_enabled)
-{
-  if (!shell_introspect->animations_enabled_valid)
-    return FALSE;
-
-  *out_animations_enabled = shell_introspect->animations_enabled;
-  return TRUE;
-}
-
 static void
 on_windows_changed_cb (GDBusProxy      *proxy,
                        ShellIntrospect *shell_introspect)
@@ -291,6 +243,29 @@ on_shell_introspect_name_vanished (GDBusConnection *connection,
     }
 }

+static void
+shell_introspect_class_init (ShellIntrospectClass *klass)
+{
+  signals[WINDOWS_CHANGED] = g_signal_new ("windows-changed",
+                                           G_TYPE_FROM_CLASS (klass),
+                                           G_SIGNAL_RUN_LAST,
+                                           0,
+                                           NULL, NULL, NULL,
+                                           G_TYPE_NONE, 0);
+  signals[ANIMATIONS_ENABLED_CHANGED] =
+    g_signal_new ("animations-enabled-changed",
+                  G_TYPE_FROM_CLASS (klass),
+                  G_SIGNAL_RUN_LAST,
+                  0,
+                  NULL, NULL, NULL,
+                  G_TYPE_NONE, 0);
+}
+
+static void
+shell_introspect_init (ShellIntrospect *shell_introspect)
+{
+}
+
 ShellIntrospect *
 shell_introspect_get (void)
 {
@@ -311,25 +286,67 @@ shell_introspect_get (void)
   return shell_introspect;
 }

-static void
-shell_introspect_init (ShellIntrospect *shell_introspect)
+GPtrArray *
+shell_introspect_get_windows (ShellIntrospect *shell_introspect)
 {
+  return shell_introspect->windows;
 }

-static void
-shell_introspect_class_init (ShellIntrospectClass *klass)
+void
+shell_introspect_ref_listeners (ShellIntrospect *shell_introspect)
 {
-  signals[WINDOWS_CHANGED] = g_signal_new ("windows-changed",
-                                           G_TYPE_FROM_CLASS (klass),
-                                           G_SIGNAL_RUN_LAST,
-                                           0,
-                                           NULL, NULL, NULL,
-                                           G_TYPE_NONE, 0);
-  signals[ANIMATIONS_ENABLED_CHANGED] =
-    g_signal_new ("animations-enabled-changed",
-                  G_TYPE_FROM_CLASS (klass),
-                  G_SIGNAL_RUN_LAST,
-                  0,
-                  NULL, NULL, NULL,
-                  G_TYPE_NONE, 0);
+  shell_introspect->num_listeners++;
+
+  if (shell_introspect->proxy)
+    sync_state (shell_introspect);
+}
+
+void
+shell_introspect_unref_listeners (ShellIntrospect *shell_introspect)
+{
+  g_return_if_fail (shell_introspect->num_listeners > 0);
+
+  shell_introspect->num_listeners--;
+  if (shell_introspect->num_listeners == 0)
+    g_clear_pointer (&shell_introspect->windows, g_ptr_array_unref);
+}
+
+const char *
+window_get_title (Window *window)
+{
+  return window->title;
+}
+
+const char *
+window_get_app_id (Window *window)
+{
+  return window->app_id;
+}
+
+const uint64_t
+window_get_id (Window *window)
+{
+  return window->id;
+}
+
+gboolean
+shell_introspect_are_animations_enabled (ShellIntrospect *shell_introspect,
+                                         gboolean        *out_animations_enabled)
+{
+  if (!shell_introspect->animations_enabled_valid)
+    return FALSE;
+
+  *out_animations_enabled = shell_introspect->animations_enabled;
+  return TRUE;
+}
+
+void
+shell_introspect_wait_for_windows (ShellIntrospect *shell_introspect)
+{
+  g_assert (shell_introspect->num_listeners > 0);
+
+  sync_state (shell_introspect);
+
+  while (!shell_introspect->windows)
+    g_main_context_iteration (NULL, TRUE);
 }
diff --git a/src/shellintrospect.h b/src/shellintrospect.h
index b187c4d..f63ecee 100644
--- a/src/shellintrospect.h
+++ b/src/shellintrospect.h
@@ -28,19 +28,21 @@ typedef struct _Window Window;
 G_DECLARE_FINAL_TYPE (ShellIntrospect, shell_introspect,
                       SHELL, INTROSPECT, GObject)

+ShellIntrospect * shell_introspect_get (void);
+
+void shell_introspect_ref_listeners (ShellIntrospect *shell_introspect);
+
+void shell_introspect_unref_listeners (ShellIntrospect *shell_introspect);
+
 const char * window_get_app_id (Window *window);

 const char * window_get_title (Window *window);

 const uint64_t window_get_id (Window *window);

-GList * shell_introspect_get_windows (ShellIntrospect *shell_introspect);
+GPtrArray * shell_introspect_get_windows (ShellIntrospect *shell_introspect);

-gboolean shell_introspect_are_animations_enabled (ShellIntrospect *introspect,
+gboolean shell_introspect_are_animations_enabled (ShellIntrospect *shell_introspect,
                                                   gboolean        *enable_animations);

-void shell_introspect_ref_listeners (ShellIntrospect *shell_introspect);
-
-void shell_introspect_unref_listeners (ShellIntrospect *shell_introspect);
-
-ShellIntrospect * shell_introspect_get (void);
+void shell_introspect_wait_for_windows (ShellIntrospect *shell_introspect);